I could see myself agreeing with rethinking the concept of a "boat race." Imagine days-long or even week-long festivals allowing all manner of race boats an opportunity in the spotlight...all in one place at one time...with different classes on different days or even simultaneously on different courses. It also provides all manner of race fans the ability to see the wares and practices of the different categories of boat racing.
However, rethinking the concept of a "race boat..." I don't think that's such a good idea. Let's face it, folks like what they like, and most folks only have a passing interest in areas outside of their likes. I'd watch little 13' inboards if I was already there, but no way in hell would I go out of my way to watch them. I'd go for the offshores, and merely stick around for the others.
The advantage is that the sponsors - in all divisions - have a larger crowd peering down on their logos and ads for longer times. It would make for good tv, too.